Battery post and connector strap mold

ABSTRACT

There is disclosed a mold assembly for casting posts and plate connector straps onto stacks of plates of lead acid type batteries wherein molten metal is circulated through one or more channels in the assembly and selectively damned to overflow into adjacent mold cavities. Cycle time and properties of the posts and connector straps are improved by constructions which impart a large thermal mass to the channel walls and a small thermal mass to the mold cavity walls. Thermal isolation of the mold cavity walls from the channel walls further enhances these conditions whereby the molds can be elevated in temperature prior to the casting operation and rapidly cooled during that operation. Cooling of the post mold cavities earlier and at a faster rate than the strap mold cavities increases post strength. A mold frame construction containing the molten metal flow channel and one or more inserts for the frame provide the desirable thermal properties while lending flexibility to the apparatus. Coolant circuits are provided for the inserts with flow paths which influence the sequence and speed of cooling of mold insert portions.

BACKGROUND OF THE INVENTION

This invention relates to improvements for battery strap and postcast-on machines of the type disclosed in U.S. Pat. Nos. 3,718,174 and3,802,488 respectively issued Feb. 27, 1973, and Apr. 9, 1974, both ofwhich issued to Donald R. Hull and Robert D. Simonton. In thosemachines, stacked battery plates and separators for a plurality of cellsmaking up a lead-acid storage battery have the respective connectionlugs on the positive and negative plates of each cell interconnected bya cast-on strap and an intercell connecting post or terminal post castas an integral portion of each strap. These casting operations areaccomplished simultaneously with the cells inverted but otherwiseoriented as they are to be in the finished battery structure. Stackedcell elements are clamped with the plate lugs extending downward. Aplurality of properly oriented mold cavities are preheated as bydirecting a gas flame over them. Molten metal, usually containing alarge proportion of lead, is circulated continuously along a channelnext to the cavities and the flame which is reducing also preconditionsthe upper surface of the metal. When desired conditions are achieved,the molten metal level is raised to overflow wiers between the channeland each mold cavity to fill the cavities, the molten metal is thenpermitted to recede, the flame is removed, and the clamped cellassemblies are positioned to immerse a portion of the plate connectinglug on each plate in the molten mass in an appropriate connector strapcavity. The cavities are then chilled, as by flowing water through thebody of the mold, and when the molded straps and posts solidifyadequately they are extracted from the mold with the plates fusedthereto.

A procedure as outlined above should be accomplished in repetitivecycles for efficient commercial utilization. Cycle time should bereduced to a minimum. It has been found that a substantial portion ofthe cycle time is involved in the heating and cooling of the mold body.Further, where the molten metal flow channels are in the mold assembly,the channel walls should not be chilled to such a degree that the metalflow is impeded during the freezing of the straps and posts. Thisrequired some degree of precision in the temperature control of the moldassembly. It has been found desirable to cool the posts, particularlythe terminal posts, at least as rapidly as the less massive straps sincethe slower cooling of the posts tends to result in mechanically weakterminals. Accordingly, greater control of localized temperature in themold assembly than has been available heretofore is desirable.

Mold expense is a significant factor in machines of the type underconsideration. It has been difficult to obtain suitable castings inwhich mold forms can be produced. The variety of cell and terminalarrangements required for lead-acid batteries has further complicatedmold construction.

In accordance with the above, an object of this invention is to improvemold assemblies for battery strap and post cast-on machines.

A second object is to decrease cycle time of battery strap and postcast-on machines.

A third object is to reduce the cost of mold assemblies.

A fourth object is to increase the control of localized thermalconditions in mold assemblies.

SUMMARY OF THE INVENTION

The above and other objects have been realized by the invention of moldassemblies in which the mold cavities are formed in bodies which areseparable from a frame body for the assembly. In one embodiment thecavities are in a plurality of modules which are constructed to minimizethe metal mass in the vicinity of the cavity walls. Coolant passages arearranged in close proximity to the post cavities and the strap cavitieswith the coolant flow arranged to pass the post cavities before reachingthe strap cavities. Coolant inlets to the assembly immediately precedethe terminal post coolant passages to insure initial cooling of theterminal posts. Coolant path interconnections between the modules areprovided while module interfaces are arranged to be in excellent heattransfer relationship to each other yet thermally isolated from theframe. Module indexing means are provided to accurately position theheight of the modules within the mold assembly frame.

Marginal flow channels for the molten metal are provided in oneembodiment of the mold assembly. The molten metal flows around theperimeter of the assembly in a split path from one longitudinal end tothe other. This concentrates the region in which heating and cooling isextreme and permits closer spacing of plate connecting straps and cellconnecting and terminal posts in the finished battery.

Another embodiment wherein advantageous heat transfer relationships areachieved with reduced mass in the material defining the mold cavitiesand close proximity of the coolant flow paths to the cavity wallsincludes a generally hollow, fabricated, mold insert fitting into a moldframe. The insert is machined to the desired cavity forms on one faceand to a single cavity on the opposite face from the bottom of whichbosses extend for the mold cavities. Baffel plates are provided in thesingle cavity to establish desired coolant flow paths. The open face ofthe single cavity is closed as by a plate welded to the insert aroundits perimeter and to the bosses so that knockout pins can enter thebottom of the mold cavities without contact with the coolant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially broken away schematic perspective view of theoperating elements of the apparatus in which the mold assemblies of thisinvention are utilized;

FIG. 2 is a perspective view of the molten metal flow path associatedwith the apparatus of FIG. 1 including the container for such metal, atypical mold assembly with marginal flow channels, a mold insert and amold frame according to this invention, and the molten metal fillingcontrol;

FIG. 3 is a plan view of a mold frame having marginal flow channels andmodular mold inserts;

FIG. 4 is an end view taken from the left hand end of FIG. 3;

FIG. 5 is a perspective view of a terminal post module or insert for theassembly of FIGS. 3 and 4;

FIG. 6 is a perspective view of an insert or module for a terminal strapand a strap of opposite polarity with an intercell connector;

FIG. 7 is a schematic diagram of coolant flow patterns in the modularcavity insert assembly of FIGS. 3 through 6;

FIG. 8 is a plan view of a mold assembly utilizing a multiple cavitymold insert mounted in a mold frame illustrative of another embodimentof this invention;

FIG. 9 is a cross-sectional view of the assembly of FIG. 8 taken alongline 9--9 thereof;

FIG. 10 is a side elevation view of the mold insert of FIGS. 8 and 9with broken away portions to show details of the construction providingcoolant jacketing in close proximity to the walls defining moldcavities;

FIG. 11 is a plan view of the bottom of the mold insert of FIGS. 8through 10 with portions broken away to reveal internal details of theconstruction; and

FIG. 12 is a sectional view of a side terminal mold portion illustratingthe coolant passages therein and taken along the line 12--12 of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An apparatus in which the mold assembly of this invention is utilized isdisclosed in FIG. 1 as comprising a base support 11 having a transferstation 12 for loading and unloading lead-acid battery cells, a pluralcell clamp and carriage 13, a lug burnishing station 14, a lug fluxingstation 15, a cast-on station 16. Controls (not shown) for the apparatusare automatically or semi-automatically operated to advance the carriage13 through a cycle from the transfer station 12 through the burnishing,fluxing and cast-on stations and back to transfer station in propertiming and sequence to result in casting cell straps on the lugs 17 ofthe positive and negative battery plates 18 of each cell to connectthose respective lugs electrically and mechanically and to formintercell connector lugs or battery terminal posts (not shown) inappropriate spatial relationship for placement in a battery case.

The apparatus includes guide rails 19 and drive means 21 for carriage 13mounted on an elevating mechanism comprising corner rods 22telescopically mounted in base, leg tubes 23 and reciprocally driventherein by cams 24. Stacks 25 of interleaved positive and negativebattery plates with suitable separators are mounted with their lugsextending downward in carriage 13 and clamped therein, typically by amachine operator actuating manual controls. When all cells are mountedthe carriage is elevated in the transfer station 12 and advanced at alevel to carry the lugs 17 through a rotating burnishing brush inburnishing station 14. The carriage then advances to a position abovefluxing station 15, is stopped and lowered to dip the lugs 17 in afluxing solution. It is then raised and permitted to drain.

At an appropriate point in the cycle of machine control, the moldassembly 26 is preconditioned for casting by heating and deoxidizing bydirecting a somewhat reducing gas flame over the surface of the assemblyfrom a burner head 27. Burner head 27 is mounted on an elevator (notshown) so that it is lowered the appropriate preheat interval ahead ofthe next cast-on operation and the flame increased to condition the moldand lead surface therein. When the temperature desired is achieved, asmay be sensed by a thermocouple 28 in the slot 29 milled in the bottomof the mold insert of FIG. 6, the flame from burner 27 is reduced to astandby level and the burner head elevated to clear the cast-on station16.

Carriage 13 is advanced in its elevated condition from the fluxingstation to the cast-on station 16 and when above the cast-on stationlowered toward the mold assembly 26 to immerse lugs 17 in molten lead inthe mold cavities for the connector straps.

Coolant is circulated through jackets around the mold cavities to freezethe posts and straps and when an appropriate temperature has beenachieved the cast post and straps are extracted from their molds bysimultaneous operation of extractors driven by a knock-out plate insynchronism with the carriage elevator. The cell units with strap andpost are then returned along an elevated path to clear the fluxingstation 15 and burnishing station 14 to the transfer station 12 where,for example, the machine operator releases the group of cells from thecarriage. In one arrangement an inverted battery casing is placed overthe upstanding bottoms of the plate stocks 25 and the carriage 13 isinverted so that the straps and posts are on the uppermost edge of thecells and the battery case (not shown) is maintained below and partiallyenclosing the clamped group of cells as they are released so they fallin place into the case.

The cast-on process outlined utilizes a mold filling techniqueillustrated in FIG. 2. A container 31 for lead is heated as by heater 32to maintain the lead molten. Molten lead is circulated through the moldassembly by a pump 33 with a suction line 34 immersed in the lead and afeed line 35 coupled to an input sump 36. From the sump 36 the leadflows through an input throat 37 to a channel 38 in communication withan output throat 39 to an output sump 41 and thence to a return line 40to the container 31. The channel 38 splits the flow of molten metal toflow through longitudinal perimeter channels 42 and a joining endchannel 43 to output throat 39 whereby lead flows around the perimeterof the array 44 of mold cavities in mold assembly 26. When it is desiredto fill the mold cavities, a gate 45 is closed across output sump 41 sothat the continued flow of molten metal into input sump 36 raises thelevel of the molten metal until it overflows the longitudinal perimeterchannels 42 into the mold cavities. Outer walls of the channels, throatsand sumps are elevated to prevent overflow of the molten metal from themold assembly 26 and gate 45 can be arranged to permit overflow of themetal to output sump 41 in the event an excess of molten metal issupplied while the gate is closed.

Apparatus for gate control is represented by a solenoid 46 coupled by arod and clevis 47 to a beam 48 pivoted at 49 and carrying the gate 45 atits opposite end. The system controls are arranged (by means not shown)to close the gate to fill the mold cavities by overflow filling and thenopen the gate to establish the desired elevation of the molten metal inthe mold cavities sufficiently ahead of the lowering of lowering of lugs17 into the cavities to avoid excessive immersion of those lugs.

It will be appreciated from the preceding discussion that a substantialdegree of precision of control of thermal conditions are required at thecast-on station 16. The channels, throats and sumps must not be cooledto a degree which would freeze off flow of the molten metal. Thecavities must be cooled sufficiently to solidify the metal forextraction in the form of straps and post. The molten metal in thecavities cannot be so hot at the time the lugs 17 are immersed that theydetrimentally affect the overlying cell assemblies 25 as by melting theplates, separators, of the lugs above the region of immersion. However,the molten metal must have sufficient heat to fuse the straps to thelugs without weak mechanical bonds or high resistance electricalinterfaces. In addition to the heating and cooling of the posts,particularly the terminal post should be controlled for strengthpurposes such that freezing of the posts is initiated prior to or atleast contemporaneously with the freezing of the frequently thinner caststrap structures. This greater cooling of the posts has been foundparticularly desirable with certain molten metal compositions. All ofthe above thermal considerations should be met in a short time toprovide a short machine cycle and increased machine productivity.

One form of mold assembly which affords the desiderata set forth isshown in FIGS. 3 and 4. Mold cavities for a six cell battery are shownincluding cavities for a negative terminal post 51, a first cellnegative strap 52 and a positive strap 53, a second cell positive strap54 and negative strap 55, a third cell negative strap 56 and positivestrap 57, a fourth cell positive strap 58 and negative strap 59, a fifthcell negative strap 61 and positive strap 62, a sixth cell positivestrap 63 and negative strap 64, and a positive terminal post 65. Thecavities 51 and 65 for the terminal post are continuous with thecavities 52 and 63 of the first and sixth cells for the connector strapsof the appropriate polarity. All other connector strap cavities includean intercell connector post cavity 66 adjacent a similar post cavity forthe strap of opposite polarity for the next cell whereby the connectionof adjacent connector posts connect the battery cells in serieselectrically.

Thermal, mechanical and fabricating advantages are realized by arrangingthe mold assembly 26 as a frame 67 having an open center 68 whichreceives one or more mold cavity inserts. In FIGS. 3 through 6, the moldcavity inserts are modularized for individual terminal post cavities 51and 65 and for the connector straps 52 through 64. Frame 67 comprisesend bosses 69 and 71, ends 72 and 73 and sides 74 and 75. A mountingcavity 77 is provided in each of the bosses to enable the frame to beclamped in the cast-on station 16 by means (not shown) and sumps 36 and41 and channels 38, 42 and 43 are formed in the frame. Frame 67 can becast and machined to its final form. In practice the walls of thechannels in which the molten metal flow paths are formed for circulationof the metal are relatively massive, as the outer walls 78 and innerwalls 79, so that they are relatively stable in temperature during thethermal cycling of the mold inserts and the walls of the mold cavities.Outer walls 78 are higher than inner walls 79 to contain the moltenmetal in the assembly 26 while permitting overflow of molten metalacross runoff surface 80 and over weir 90 inward when the gate 45 isclosed. The open center 68 is formed to provide a receptacle for themold inserts which at its upper surface is fitted closely enough toavoid the leakage of molten metal as it rises to flood the region of theinterface between the inner perimeter 81 of the frame and the outersides 82 of the inserts. The frame 67 is machined to its finaldimensions to provide simultaneous overflow filling of the several moldcavities and suitable molten metal tight mating and fastening surfaces.

Bores 83 are tapped for pipe couplings to the feed and return lines 35and 40. The reduced thickness of the inner or web portion 84 of theframe is bored and tapped on its upper surface to receive cap screws 85which retain seal plates 86 against the upper face of web 84 and of theend mold inserts 87, 88, 89, 91, 92 and 93. The lower face of web 84 isalso machined at 94 to receive a lock plate 95 fitting a keyway 96 ineach mold insert. Bores tapped for screws 97 are provided in surfaces 94to retain the lock plates 95.

Modular mold inserts are arranged in two longitudinal rows. They areseparated along those rows at adjacent connector post cavities 66. Thusas viewed in the upper row of FIG. 3 insert 89 has its post cavity 66adjacent to insert 98 having a left-hand post cavity 66 separatedtherefrom by a cell divider 99. Insert 98 includes two strap connectorcavities and two connector post cavities since no intercell connectorpost is required in the upper row between the second and third cells.Similarly, inserts 101 and 102 include two connector strap cavities.

Alignment of inserts 89, 98, 101 and 93 of the upper row, and inserts88, 102, and 92 of the lower row is established and maintained by a key103 fitted into longitudinally centered keyway 104 between the upper andlower rows and by locking plates 95 fitting into outer keyways 96 of theupper and lower rows. Terminal post cavity inserts 87 and 91 are clampedbetween seal plates 86 bearing against the upper face 105 of the insertsand lock plate 95 bearing against lip 106 where the distance betweenface 105 and lip 106 is the same as that between the upper faces of theother inserts and the upper lip of lock plate receiving keyway 96.

The adjacent faces of the inserts are machined flat to provide intimatecontact and therefore high heat transmission between inserts. Coolant issupplied to each insert through a circuit individual to each. Thesecircuits are made up of a plurality of intersecting bores and cavitieswith certain of the bores provided with individual tapped regions forthe reception of pipe couplings. The walls between the coolant passagesand the mold cavity in each insert are relatively thin, ranging fromabout one-eighth to five-sixteenths of an inch and usually about onequarter of an inch in thickness and no metal-to-metal interfaces betweenthe primary passages and the cavities are permitted in order to insurerapid heat transfer from the cavities when coolant is introduced intothe passages. Coolant inlets and passages are best seen in FIGS. 5 and 6for typical inserts 87 and 88. In insert 87 an elongate terminal cavity51 and a cavity 107 for a base portion integral with the terminal andcoupling it to the connector strap formed in cavity 52 of insert 88 arein close proximity to coolant passages 108 and 109 paralleling thelength of the terminal cavity and interconnecting coolant passages 111paralleling the bottom of cavity 107. The lower portions of the boresforming passages 108 and 109 are tapped to receive pipe couplingscommunicating with the coolant supply and controls. The outer ends ofbores 111 are pluged as at 110. The connector strap cavities andintercell connector post cavity 66 are similarly in close proximity tocoolant passages in insert 88 of FIG. 6. There bores 112 and 113 extendfrom the underside of the insert into the milled slot 114 extending overmuch of the length of insert in a position closely adjacent andessentially coincident with a projection of cavities 52 and 54 into thedepth of the insert. This coolant jacket is closed by a bar like fillerinsert 115 in the side of mold insert 88 as by a weld bead. It will benoted that bore 112 is closely adjacent the cavity 66 to efficientlycool that cavity. Again the outer portions of bores 112 and 113 aretapped to accommodate threaded pipe couplings.

The coolant circuit shown in FIG. 7 is arranged to maximize the coolingeffect on the terminal cavities by introducing the cold coolant at thesebores for those passages. The coolant is also passed serially throughhalf the inserts in two parallel circuits which parallel the terminalcoolant circuits and is withdrawn from a central region. A supply ofcoolant 116 is passed through a coolant control 117 which initiates andterminals the flow of coolant and, if desired, admits a flow of a dryinggas from a source (not shown) following completion of the coolant flowin accordance with the sequencing of the machine controls. Flow pathsare shown split at T 118 and again at Ts 119 and 121. Throttle valves122 are provided to each mold assembly input 123, 124, 125 and 126 tocontrol the amount of coolant passed through the inserts or moldmodules. An input flow path 123 and 125 is individual to each terminalmodule 87 and 91 so that the coolant flows along the terminal columns inpassages 108 and 109, beneath the terminal strap cavity 107 in passages111 and through outlet line 127 to outlet 128. The lug connector strapcavity walls are cooled by collant flow as from input path 124 through abore 129, a milled cavity 131 and a bore 132 in insert 89, throughconnector tube 133 to insert 88 and its passages 113, 114 and 112 toconnector tube 134, thence to insert 98 through its coolant passages toconnector tube 135 to insert 102. Coolant flow is illustrated by thearrows in FIG. 7. In insert 102 the coolant flows from each end passage136 and 137 through the milled internal cavity 138 to the central exitpassage 139 and then to outlet line 141.

As in the case of the exemplary modules 87 and 88 of FIGS. 5 and 6,coolant cavities are provided in the bodies in close proximity to theirmold cavity walls as by locating milled cavities close to the bottom ofthe strap cavities and the bores from the bottom sides of the inserts tothe milled cavities close to the intercell connector posts.

Another consideration in the insert construction and placement ofcoolant passages and conduits is the need for knockout pins into thedeep cavities of the mold inserts. As best seen in FIG. 4, a knockouttable 142 is located beneath the mold assembly 26 and is coupled to thecarriage elevating mechanism (by means not shown) to be lifted insynchronism with the lifting of the carriage 13 and the cell stacks 25after the straps and posts have been cast.

An ejector back-up plate 143 is mounted on the knock-out table andsupports an ejector plate 144 from which ejector pins 145 and 146 extendupward in registry in the horizontal plane with each of the intercellconnector post cavities 66 and from which terminal post ejector pins 146extend upward in registry with the terminal post cavities 51 and 65.Ejectors 147 and 148 conforming to the uppermost face of the intercellconnector posts and terminal post respectively are secured as by athreaded connection into tapped bores on each ejector pin 145 and 146.Ejectors 147 and 148 enter passages 149 and 151 as shown in FIGS. 5 and6 extending from the under surface of the inserts to the bottoms of thepost cavities 66, 51 and 65. The ejector assembly is arranged to provideclearance for all coolant connector tubes 133, 134 and 135 and externalconnections.

It will be noted from the above description that the mold assembly ofFIGS. 3 through 6 provides a stable base frame which in the perimeterfilling arrangement offers a substantial mass of high thermal capacityfor the continuously fed molten metal and a group of mold inserts ormodules which are thermally isolated from the frame yet clamped togetherfor effective thermal conductivity between each other. An arrangementhas been illustrated in FIG. 7 which insures controlled and effectivecooling of the terminal posts and rapid cooling of all cavity walls forshort cycle times. Alternative cooling arrangements are alsocontemplated with the modular mold structure. Further interchange ofmold inserts is available conveniently as by the replacement of a failedor worn insert or the substitution of a different cavity form. Thusterminal forms can be altered without changing the connector straps andposts.

Modular mold assemblies can be arranged with individual coolant inputsfrom the collant supply 116 to each moduel where greater speed or moreprecise control of relative cooling in the individual modules isdesired. They also can be arranged with the terminal post modulesconnected in a serial coolant circuit with the remainder of the assemblyso that the cold coolant is initially applied to the passages of theterminal posts and thereafter passed through the connector strap andpost modules.

In practice the modular mold assembly is formed by machining the roughframe casting to form the finished frame 67 with the desired open centerconfiguration 68 for accommodating mold inserts and the desired moltenmetal flow channel configuration for the perimeter channels or a centralchannel as the case may be. Inserts are then formed to their externalfinished dimensions over their mounting and mating faces and theirreference surfaces including keyways 96 and 104 and lip 106 are formed.Then the coolant passages are milled, bored and tapped and theconstruction apertures closed as by welding in filler plates 115 andclosing the ends 110 of bores 111. The inserts are then machined fortheir terminal and connector post cavities 51 and 66 and the ejectorpassages 151 and 149 to those cavities. Inserts are then keyed togetherand mounted in the frame for machining of their upper faces and finalmachining of the adjacent frame surfaces.

The upper surface of the mold assembly should be generally horizontal toinsure uniform flow of molten metal to all cavities when gate 45 isclosed and the metal level is raised. As best seen in FIGS. 2 and 4, thesurfaces over which the molten metal flows include the bottoms and sidesof the sumps, throats and channels 36, 37, 38, 39, 41, 42 and 43. Whengate 45 is dropped in its guide slots 153 to close off flow to returnline 40, the molten metal level rises above inner wall 79 to flow ontoupper surface 80 and over weir 90 into cavities for straps and terminaland connector posts. The level of the molten metal does not exceed theupper limit of outer wall 78 since gate 45 permits its overflow tooutlet sump 41 before that occurs. After filling is complete for exampleas determined by a timer set for the rate of molten metal flow, the gate45 is raised, the molten metal level recedes and that metal in the moldsis maintained at a level determined by the height of weirs 90. It is tobe appreciated that the final machining of the mold faces and theheights of the cell dividers 99 establish laterial limits on thecavities of the various straps and posts at least as high as the weirs90, so that upon the receding of the molten metal each strap puddle isdistinct from all other puddles and the puddles freeze in individual,mechanically and electrically isolated straps.

FIGS. 8 through 11 disclose another form of mold assembly which provideseffective thermal cycling for the cast-on techniques described. Thismold assembly 161 has a frame 162 which can be formed from the samecasting as frame 67 of FIGS. 3 through 6. The open center 163 of frame162 is formed to accommodate a manifold type of mold insert 164 which isfabricated as a unit containing the twelve connector strap cavities, tenintercell connector post cavities and two terminal post cavities of asix cell storage battery. Since the terminal posts to be formed are fora side terminal battery in the illustrated embodiment, the plan outlineof open center 163 and insert 164 contain terminal extensions as bestseen in FIGS. 8 and 11. The assembly includes the extractors for eachpost cavity formed as paired knockout pins 165 and 166 for the connectorposts and terminal posts respectively and driven by an upper and lowerejector plate 167 and 168 from knockout table 142. Insert 164 is securedto the frame by lock plates 169 and cap screws 171 into the frame.Perimeter overflow filling of the molds is utilized with perimeter flowchannels, sumps, throats and a gate of the general form discussed withrespect to FIGS. 3 through 6 and therefore assigned the same referencecharacters. Surfaces over which the molten metal flows are machined toprovide the desired matches with insert 164 to carry the molten metal toand from the region of the mold cavities.

Manifold insert 164 is a single water jacketed body fabricated from asuitable material such as a block 172 of cold drawn machine steel whichis machined from its front or upper face 173 to form the mold cavitiesand from its rear or lower face 174 to form a water jacket or coolantflow path. More particularly, the block 172 is milled from its lowerface 174 to a depth which leaves an upper face wall thickness adequatefor the milling of connector strap cavities, for example in a 1.500 inchthick block it can be milled 1.000 inch deep to an inner face 175 ofgenerally rectangular form having bosses 176, 177, 178, 179 and 181, endwalls 182 and side walls 183 and 184. Bosses 176 through 181 providematerial in which connector post mold cavities 185 are formed from upperface 173 as by electric discharge machining.

The rear wall 186 of the mold insert water jacket is formed by a platehaving keyways 187 formed in each end to register with keyways 188 inendwalls 182. Keys 189 are fitted into keyways 187 and 188 to alignplate 186 whereby externally threaded sleeves 191, 192 and 193 welded tothe outer face of plate 186 in registry with apertures 194 providecouplings for coolant input lines at 191 and 192 and an exhaust line at193. Plate 186 is also apertures at 195 in registry with each of bosses176, 177, 178, 179 and 181 where apertured 195 are within theprojections of the respective bosses to enable a weld bead 196 to belaid around the inner wall of each aperture 195 in sealing relation tothe lower face of the registering boss. A sealing weld bead 197 is alsolaid around the perimeter of plate 186 to seal the water jacket bysealing plate 186 to the walls 182, 183 and 184. Before application ofplate 186 to block 172, coolant directing baffels 198 are tack welded tothe inner face 175 to cooperate with bosses 176 and 181 in directing thein-flow of coolant toward the terminal extensions 201 and 202 whereby asubstantial flow of cold coolant is applied to the terminal cavityregions as in the embodiment of FIGS. 3 through 6. Other coolant pathsto the main body cavity are available as between the wall 183 and boss176, between 176 and baffel 198 and between baffel 198 and wall 184.

Coolant cavities 203 and 204 are formed in close proximity to theterminal post cavities of extensions 201 and 202 by milling into therear face 205 of the extensions and closing that face with a fillerinsert plate 206 sealed, as by weld bead 207, to the wall of the milledcavities. A slot 208 milled to a depth 209 in each of the distal faces211 and 212 of extensions 201 and 202 provides a coolant passage aroundthe outer side of the terminal post cavities with a closure plate 213forming its outer wall when sealed by weld bead 214. Bores 215 and 216extend into faces 211 and 212 and through main cavity sidewall 184 toprovide inlet and exit coolant passages communicating with the maincoolant cavity on the input and exit sides respectively of baffels 198.

The mold cavities are formed in the upper face 173 of block 172 bymilling strap cavities 217 in the planar form shown in FIG. 8 and of thecross-section shown in FIG. 9. Cavity legs 218 and 219 for the negativeand positive terminal posts extend along the face of extensions 201 and202 and can be formed by milling. The intercell connector post cavities185 are of the form of cavities 66 of FIGS. 3 through 6 and are formedin pairs in bosses 176, 177, 178, 179 and 181 so that they do not breakthrough the boss walls and into the coolant cavity. Electric dischargemachining permits these cavities to be formed with precision from face172 such that one suitably tapered cavity can have a central groove 222transverse of the longitudinal dimension of the insert into which isplaced a divider plate 223 to separate the machined cavity into the twospaced separate cavities 185. Paired bores 224 for reception of knockoutpins 165 extend normal to the general major plane of the manifold insert164 through the bosses 176, 177, 178, 179 and 181 and into each of theconnector post cavities 185. Thus, the cavity walls are in closeproximity to the coolant for rapid cooling being spaced from the coolantonly by the thickness of the remaining wall portions of their respectivebosses.

Terminal post cavities 225 and 226 are formed at the ends of legcavities 218 and 219 so that they extend below coolant cavities 203 and204 and bores 215 and 216 whereby water is circulated around all sidesof cavity 225 in extension 201 and similarly around cavity 226 inextension 202. In addition cavities 203 and 204 are close to the undersurface of leg cavities 218 and 219 to rapidly enable the transmissionof heat to the coolant from those cavity walls.

A thermocouple pocket 227 is located in block 172 close to theundersurface of leg cavity 218 and between coolant cavity 203 and themain coolant cavity whereby a thermocouple can be located close to themold cavities for machine control purposes.

The embodiment of FIGS. 8 through 11 lends itself to convenientmanufacture by milling the major face contours of the block 172, as thedividing ridge 228 between the aligned connector strap cavities, theweirs 229 adjacent each connector strap cavity and the runoff surfaces231 from the weirs to the flow channels for the molten metal. Thin wallsand substantial contact areas between the coolant and the walls insurerapid cooling of the cavities and the metal therein. Simple framecastings which have at least a substantial range of application todifferent molds and do not require the degree of perfection and freedomfrom flaws that has been dictated previously where mold cavities wereformed in the castings can be employed. Thus, the mold assemblies aremore trouble-free and superior than those disclosed in the aforenotedpatents.

The thin walls of the manifold insert 164 particularly in the portionsof that insert in which the mold cavities are formed offers theadvantage of relatively low thermal mass in the mold cavity walls.Further, the separation of the sidewalls of bosses 176, 177, 178, 179and 181 from the side wall of the inner perimeter of frame 162 increasesthe cooling rate for the intercell connector mold cavities. Thesubstantial volume of the coolant passages around the terminal post moldcavities 226 enhances their cooling rate. Voids over much of theinterface region between the side walls of the insert 164 and the frame162 as at 235 of FIG. 9 tend to isolate the hot and large thermal massof frame 162 from the thermally cycled insert 164. Similar voids can beprovided on the terminal extensions 201 and 202 as shown in FIG. 9 atthe space 236 between closure plate 213 and the frame.

It is to be appreciated that other forms of mold assemblies offering theadvantage of maintaining a base structure such as frame 162 and the flowchannel for molten metal contained in that base above the meltingtemperature of that metal while cycling the temperature of insert bodiescontaining mold cavities between a temperature above and below themelting temperature of the molten metal are within the concepts of thisinvention. That is, a base structure containing a molten metal flowchannel can be arranged to have mold bodies maintained adjacent the basewith the upper margins of the flow channel in molten metal flowcommunication with the upper margins of mold cavities so that uponelevation of the upper surface of the molten metal in the flow channelabove the channel margins it will overflow into the cavities. Sucharrangements by virtue of the base to insert interface resistance toheat flow, and/or the provision of voids or other thermal barriers inthat interface region, even while maintaining a molten metal overflowsurface between the base and insert, tends to thermally isolate theinsert from the base and enable its rapid thermal cycling.

Further enhancement of thermal cyclcing of the insert and mold cavity isrealized by reducing its thermal mass relative to the thermal mass ofthe base and by providing means to selectively circulate coolant throughthe insert while the base is free of coolant passages and relativelystable in its temperature. In the example, a base blank for a frame typebase has major body dimensions about two inches by eight inches byfourteen and a half inches with end bases about two inches wide and aninch and three quarters long. The walls of the flow channel arerelatively thick with bottom walls and outer side walls about one halfinch thick and the inner side walls varying in thickness to accommodatethe insert or inserts. The inserts on the other hand have relatively lowthermal mass and thin walls between the coolant passages and the moldcavities. In the embodiment of FIGS. 8 through 12 the insert is about aninch and a half thick, about three and a half inches wide and nine andthree quarters inch long in the primary rectangular section withterminal extensions 201 and 202 about 11/4 inches thick, and 11/2 by21/2 inches. Most walls in this insert are about 1/4 inch thick.

The hollow form of insert of FIGS. 8 through 12 can be modified in manyforms to provide intimate relationships between the coolant flow pathsand the mold cavity walls. The preferential cooling of the terminalmolds might be accomplished by providing coolant inputs at theextensions 201 and 202 rather than the baffles and bosses illustrated asdirecting flow to their cooling passages. Additional baffeling or inputports for coolant can be utilized.

While overflow filling of the molds from perimeter channels has beenshown, it is to be understood that an internal channel might also beincorporated in this mold assembly construction. Other connector strap,connector post, and terminal post structures or combinations can beformed in this type of construction. Alternative assembly techniques andstructures wherein mold cavities and coolant cavities are separated bythin walls and formed in bodies of low thermal mass having thermalisolation from bodies of relatively large thermal mass containing flowchannels for molten metal are contemplated within this invention.Accordingly, the above disclosure is to be read as illustrative of theinvention and not in a restrictive sense.

We claim:
 1. A mold assembly for casting elements onto storage batteryplates comprising a base having a contoured upper surface including agenerally horizontal flow channel having an inlet and an outlet spacedapart along the length of said channel for guiding the flow of moltenmetal along essentially the entire length of said channel between saidinlet and outlet, a perimeter wall contiguous to portions of said flowchannel of a first height sufficient to constrain molten metal undernormal operating conditions of said assembly, a runoff surfacecontiguous to portions of said flow channel having a second height lesssaid first height whereby the assembly is adapted to pass metal oversaid runoff surface when the level of molten metal in said channel israised above said second height and below said first height under normaloperating conditions of said assembly, said base being free of moldcavities in which elements are cast; an insert having at least a portionof each of a plurality of mold cavities in its upper surface and adaptedto be mounted adjacent said base and separable therefrom, said moldcavities for the elements to be cast being entirely contained upon saidinsert; means mounting said insert contiguous with said runoff surface;said insert having a contoured upper surface in molten metal flowcommunication with said runoff surface and being in molten metal tightmating relationship thereto; a heat flow barrier means between said baseand said insert; said base having a large thermal mass whereby moltenmetal flowing in said flow channel is maintained molten; said inserthaving a small thermal mass relative to that of said base in the portionthereof defining walls of the mold cavities; and a coolant jacketintegral with said insert and extending over a majority of the undersideof said upper surface upon which said mold cavities are containedwhereby molten metal in said cavities can be solidified by admission ofcoolant to said insert jacket without cooling said base to a degreeimpeding the flow of molten metal in said flow channel.
 2. A moldassembly according to claim 1 wherein said base is free of coolantpassages in the body thereof.
 3. A mold assembly according to claim 1wherein said barrier means is characterized as a void.
 4. A moldassembly according to claim 1 including a second insert having at leasta portion of each of a plurality of mold cavities in its upper surfaceand adapted to be mounted adjacent said base and separable therefrom,said mold cavities for the elements to be cast being entirely containedupon said second insert; means mounting said second insert contiguouswith said runoff surface; said second insert having a contoured uppersurface in molten metal flow communication with said runoff surface andbeing in molten metal tight mating relationship thereto; and a heat flowbarrier means between said base and said second insert; said secondinsert having a small thermal mass relative to that of said base in theportion thereof defining walls of the mold cavities; and a secondcoolant jacket integral with said second insert and extending over thepreponderance of the underside of said upper surface of said secondinsert upon which said mold cavities are contained whereby molten metalin said cavities can be solidified by admission of coolant to saidsecond insert jacket without cooling said base to a degree impeding theflow of molten metal in said flow channel.
 5. A mold assembly accordingto claim 1 wherein at least certain of said plurality of mold cavitiesare discrete and spaced apart.
 6. A mold assembly according to claim 1wherein the depth of at least a first one of said mold cavities isgreater than at least one other of said mold cavities; and means forpreferentially directing coolant to portions of said coolant jacketproximate said first one of said mold cavities.
 7. A mold assembly forcasting elements onto storage battery plates comprising a base framehaving an aperture through its thickness and having a contoured uppersurface including a generally horizontal flow channel having an inletand an outlet spaced apart along the length of said channel for guidingthe flow of molten metal along essentially the entire length of saidchannel between said inlet and outlet, a perimeter wall contiguous toportions of said flow channel and contiguous to the outer limits of theupper surface of said frame of a first height sufficient to constrainmolten metal under normal operating conditions of said assembly, arunoff surface contiguous to portions of said flow channel and saidaperture having a second height less than said first height whereby theassembly is adapted to pass molten metal over said runoff surface whenthe level of molten metal in said channel is raised above said secondheight and below said first height under normal operating conditions ofsaid assembly, said base being free of mold cavities in which elementsare cast; an insert having at least a portion of each of a plurality ofmold cavities in its upper surface and adapted to be mounted in saidaperture of and adjacent said base frame and separable therefrom, saidmold cavities for the elements to be cast being entirely contained uponsaid insert; means mounting said insert adjacent said base andcontiguous with said runoff surface; said insert having a contouredupper surface in molten metal flow communication with said runoffsurface and being in molten metal tight mating relationship thereto; aheat flow barrier means between said base and said insert; said basehaving a large thermal mass whereby molten metal flowing in said flowchannel is maintained molten; said insert having a small thermal massrelative to that of said base in the portion thereof defining walls ofthe mold cavities; and a coolant jacket integral with said insert andextending over a preponderance of the underside of said upper surfaceupon which said mold cavities are contained whereby molten metal in saidcavities can be solidified by admission of coolant to said insert jacketwithout cooling said base to a degree impeding the flow of molten metalin said flow channel.
 8. A mold assembly according to claim 7 whereinthe depth of at least a first one of said mold cavities is greater thanat least one other of said mold cavities; and means for preferentiallydirecting coolant to portions of said coolant jacket proximate saidfirst one of said mold cavities.
 9. A mold assembly according to claim 8wherein said insert is a hollow body providing in its hollow interiorsaid coolant jacket and wherein said means for directing coolant is acoolant flow barrier within said hollow interior.
 10. A mold assemblyaccording to claim 7 wherein said base frame is free of coolant flowpassages.
 11. A mold assembly according to claim 7 wherein saidhorizontal flow channel extends along opposite sides of said base frameand said runoff surface extends along opposite sides of said base framefrom said contiguous flow channel portions to the inner margins of thecontoured upper surface of said base frame.
 12. A mold assembly forcasting elements onto storage battery plates comprising a base having agenerally horizontal flow channel having an inlet at one end and anoutlet at another end for guiding the flow of molten metal; an inserthaving mold cavities in its upper surface and having a hollow bodyproviding in its hollow interior coolant flow paths and including bossesextending across the thickness of said hollow interior, said bosseshaving said mold cavities extending from the upper surface of saidinsert at least partially through the portion of the bosses within saidhollow region; said base being a frame having an aperture through itsthickness adapted to mount said insert and being separable therefrom;said coolant flow paths in said insert being in close proximity to eachof said mold cavities; said base having a large thermal mass wherebymolten metal flowing in said flow channel is maintained molten; saidinsert having a small thermal mass relative to that of said base in theportion thereof defining the walls of the mold cavities whereby moltenmetal in the mold cavity can be solidified by admission of coolantwithout cooling said base to a degree impeding the flow of molten metalin said flow channel; and means mounting said insert with an uppersurface thereof adjacent said mold cavity in molten metal flowcommunication with an upper margin of said flow channel whereby theelevation of the level of molten metal in said flow channel to overflowits upper margin will admit the molten metal to said mold cavities andthe depression of the level of molten metal following the overflow willestablish a level of molten metal in said mold cavity at a level of theupper face of said insert adjacent said mold cavity.
 13. A mold assemblyaccording to claim 12 wherein said insert has an upper surface having athickness above said hollow region and having mold cavities in saidthickness whereby coolant in said hollow region is in contact with thebottom walls of said mold cavities.
 14. A mold assembly according toclaim 12 wherein said bosses have passages from the major face of saidinsert opposite said upper major face and adapted to receive moldextractors, said mold extractor passages being isolated from saidcoolant flow paths.